Head lamp



April s, 1928.

F. G. ENGLE 31401211 lo c 6H0: new

Patented Aprr 3, 1928.

IRAN! 0.

ENGLE, NEW YORK, N. Y.

nan am.

Application filed April 8, 1925. Serial No. 81,711.

The present invention relates to improvements in head-lamps for automobiles and the like, and more particularly to that type disclosed in my application for Letters Patent, Serial. No. 759,184, filed December 31,

The primary object is to provide means 'whereby much of the light lost in the lamp shown in the aforesaid application is utilized and properly directed, and incidentally the driver ofan approaching car or vehicle is shielded from the direct light from the filament.

Another object is to direct such light as 15 may be reflected by the glass surface of the bulb into a beam conforming to the shape described in the aforesaid application.

In the accompanying drawings:

Figure 1 is a vertical sectional view somewhat diagrammatic in its character, illustrating one embodiment of the invention,

Figure 2 is a sectional view on the line 2-2 of Figure 1,

Figure 3 is a vertical sectional view of a modified form of construction, p

Figure 4 is a similar view of still another embodiment of the invention,

Figure 5 is a sectional view of another embodiment of the invention.

As in the original disclosure appearing in Serial No. 759.184. a parabolic reflector 5 is employed, this reflector terminating at the focal plane, indicated at 6. The focal point 7 is located at a distance from the vertex 8, equal to one-fourth of the diameter of the local plane 6.

Extending from said vertex 8 is the socket or mounting 9 in which an incandescent electric lamp 10 is carried. This'lamp is provided with an illuminating element in the form of a filament 11. By referring to Figure 2, it will be noted that the filament constitutes a segment of a circle concentric to the focal point 7 and by reference to Figure 1 it will be observed that this filament is locate/din the focal plane 6.

As explained in the above-mentioned application a path of light will be created, comprising substantially three-fourths of a circle, leaving oue-fourthof such circle unilluminatcd. and the illuminated portion is so disposed that it will be out of the path of a person approaching the lam The outer half of the light from the filament in the above-mentioned disclosure is not however projected, and thus in great measure is lost, and the present invention is intended to direct this light so that it will add to the amount delivered, from the lamp in the above desired path.

This is accomplished by'providing an internal reflector 12 arranged in front of the lamp, and in reverse relation to the parabolic refiector5. The reflector .12 is in the form of part of a parabolic spindle, or in other words, a figure generated by the revolutlon of a parabola. about a chord dicular to its axis, in the present case, a focal chord. As will be noted the reflector 12 is approximately one-half of such spindle and its interior constitutes a reflector, which preferably terminates at its.

rear end at the focal plane 6. With this construction, the rays of light emanating 'irom the filament 11 and projected in ad- Vance of said filament,-will be diverted by the reflector 12 back to the reflector 5, and then projected with the other rays of light. For example. a ray of light as a will strike one side of the reflector, thence be directed, as shown at 6. across the same to the opposite side, returned rearwardly. as shown at 0, through the filament at the point from which it emanated to the reflector 5, and

then projected forwardly, as shown at d. The light thus obtained from the head lamp is materially increased in intensity and yet is controlled in the manner explained in Serial No. 7 59.184.

This reflector may be a separate element from the lamp. as shown in Figure 1, or the lamp bulb itself may have its front end formed as part of the spindle, and as shown at 12. in which case it is provided with a reflecting surface as will be obvious.

In both of thcsc structures a small amount of light is still lost. because the main reflector 5 is shaded from part of the light reflected from the internal reflector by the mounting or socket 9. as shown by the dotted lines e. By truncating the reflector 12 or 12. as shown at 12. and placing across the truncated end a lens 12. the amount of light thus lost and indicated by the portion 7' in Figure 1, is thus projected and acconvex lens will control passage of this light into the desired sector, with a corresponding gain in cfiicicucv. since it avoids reflection.

perpenccIn Figure 5 the bulb is in the form of a substantially complete parabolic spindle, with the exception of the rear end. which carries the usual mounting element; The

' .same etfect.- As is well-known, in any glass bulb not all of the light passes through the glass initially, but some of it is reflected back from the surface it first strikes and later passes through at another point. This form-s an image of the filament, reduced in brilliancy, but not negligible. By forming the rear half of the bulb of spindle-shape, the result is an image coinciding and erect with the filament, and thereby projecting light in the desired form of beam. Taking, for example, a ray of light. as e emanating from a point of the filament, a part of this ray is projected on through the glass at f. and striking the reflector 5 is projected forwardly, as shown at g. A part, however, is reflected by the glass. as shown at h, and this is again subdivided, part passing through the glass at z, striking the reflector 5. and being reflected downwardly. as illustrated at k. The other portion is again reflected, as indicated at Z. passing through the point of origin in the filament, and again it is entirely reflected by the reflecting surface (Z, and as shown at m across to the opposite side, thence through the point of origin and out through the glass to the main reflector. That part of the light which passes through. as shown at 2' and k is the only stray or discordant light, that is, it is not projected in the desired beam.

From the foregoing. it is thought that the construction, operation and many advantages of the herein described invention will be apparent to those skilled in the art, without.- further description, and it will be understood that various changes in the size, shape, proportion and minor details of construction may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

What I claim, is:

1. In a head lamp, the combination with a reflector of substantially parabolic form terminating substantially at the focal plane, of a lamp having its illuminating element in said focal plane and out of the focal point, and an internal reflector in reverse relation to the first reflector and being in the substantial form of part of a parabolic spindle whosc axis intersects the said focal point and is substantially perpendicular to the focal plane.

2. In a head lamp, the combination with a reflector of substantially parabolic form, of a lamp having its front end in advance of the focal plane and in the form of part of a parabolic spindle and said end having an internal reflecting surface, said lamp having a filament, an extended portion of which lies in the focal plane and extends around the focal point outside said point.

3. In a head lamp, the combination with a reflector of substantially parabolic form, of a lamp having an internal reflector on its front portion in advance of the focal plane and in the form of a truncated parabolic spindle, said lamp having a filament. an extended portion of which lies in the focal plane and extends around the focal point outside said point.

4. In a head lamp. the combination with a reflector of substantially parabolic form, of a lamp having an internal reflector on its front portion in advance of the focal plane, said lamp being in the form of a truncated parabolic spindle, and a lens extending across said truncated end, said lamp having a filament, an extended portion of which lies in the focal plane and extends around the focal point outside said point.

5. In a head lamp. the combination with a reflector of substantially parabolic form. of a lamp having a bulb substantially in the form of a parabolic spindle and having portions extending behind and in front of the focal plane of the reflector, said lamp having a filament within the bulb. an extended portion of said filament lying in said focal plane and extends around the focal point outside said point.

6. In a head lamp, the combination with a reflector of substantially parabolic form. of a lamp having a bulb substantially in the form of a parabolic spindle and having portions extending behind and in front of the focal plane of the reflector. said lamp having a filament within the bulb and having an extended portion lying in said focal plane, and extending around the focal point outside said point the portion of the bulb in advance of the focal plane having a rearward ieflecting surface conformin to the contour of said portion of the bulb.

In testimony whereof, I afiix my signature.

FRANK G. ENGLlC. 

